I needed a new winter bag for a trip this past February and am a die-hard hammock camper. I have a Stephenson's Warmlite down air mattress (DAM) and a home-brew Speer SPE-type thingie with 3 wings on each side. I use a top-loading home-made Speer-type hammock.
I went with the Wiggys -20 Ultima Thule based on recommendations from fellow Scout leaders. I also got the large compression sack and the booties.
The reasons the recommenders gave are warmth, durability, the lifetime guarantee, and the fact that it breathes body moisture out of the bag. They tell tales of waking up warm with the outside of the bag covered in frost from perspiration that went right through the insulation and froze, yet they remained extremely comfortable even at -20. I perspire a great deal and knew I'd never be able to make it with a down bag. Since I needed a synthetic bag, the Wiggys bag was my first choice.
There are no baffles on a Wiggys bag. The insulation is continuous and permanently placed between the inner and outer nylon shell parts. It's a little weird looking at first. It's guaranteed to never separate or shift.
This is not a lightweight bag, period (I weighed it on the scale at work at about 6.5 pounds). It is very hard to get into the compression sack with mittens on (which is a requirement for me when camping in really cold weather). Those are the two drawbacks, but they are pretty big ones.
The bag really keeps me warm, however. I was overheating at 10 degrees (we were snowshoeing in and I did not know what to expect, so I took the arsenal). I would not have needed this bag at those temps.
If I had this to do all over again, I would still buy the Ultima Thule, but I would have had him make a custom bag with the zipper up the middle instead of the side. It is a very lofty bag and I get inside my bags in cold weather. The zipper up the middle would make it really easy to get into. He charges something like $50 extra for that customization.
I will be replacing my +20 EMS bag with a Wiggys bag sometime after I pay off the recent repairs on my two cars, and I WILL order that one with the zipper up the middle. I am sold on his concept, his materials and his commitment to quality.
I hope this helps.